According to
Woman 'fined $500 over free Delta Air Lines flight apple' - BBC News
The apple was handed out in a plastic Delta Air Lines bag. Ms Tadlock said she did not remove it from the bag, instead putting it in her baggage for the second part of her journey to Denver, Colorado.
When the apple was found, Ms Tadlock told the agent that she had just received it from the airline and asked whether she should throw it out or eat it.
Instead the agent handed her a $500 fine.
When you put all that together this really does seem ridiculous, and Delta should have warned their passengers too.
EDIT: Just beaten by previous post!